Also: https://github.com/sparksuite/simplemde-markdown-editor/issues/430 
for change to simplemde to disable github markdown.

This may be needed unless we are using a markdown in the backend that
can have the github markdown variant enabled.

Can simplemde do a rest query to get formatted output? If so then
msg6814 and msg6815 may provide a solution.

Also: https://www.npmjs.com/package/@amrn/simplemde mentions:

  renderingConfig: Adjust settings for parsing the Markdown during 
previewing (not editing).
    singleLineBreaks: If set to false, disable parsing GFM single line 
breaks. Defaults to true.

maybe this can be added to the client side if it does the right thing?